Diacetone-2-ketogulonic acid can be made by electrochemical oxidation of diacetone-sorbose by passing an electrical current through an aqueous alkaline solution containing diacetone-sorbose. Diacetone-2-ketogulonic acid, an intermediate for the preparation of ascorbic acid, is obtained in relatively high yields.
However, known processes have certain disadvantages. In comparatively long electrochemical operations, current and material yields are reduced and yields of the desired end product are not reproducible.
A further disadvantage of known processes is that diacetone-sorbose used can not be oxidized quantitatively under technically and economically acceptable conditions and that, in some cases, conversions as low as about 20% of theoretical are achieved.
Good results can be achieved by adding nickel salts to the electrolyte solution but, in this process, the life of the anode is limited by accretion of voluminous deposits of nickel oxide. Also, special precautions are required to prevent toxic nickel salts remaining in the electrolyte solution from being disposed of in the waste water.
Addition of water-soluble co-solvents can prevent or retard poisoning of the cathode. In Chemie-Ingenieur-Technik, 46, (1974) pages 569-597, various organic solvents are mentioned for this purpose. However, in anodic oxidation of diacetone-sorbose, use of these solvents produces no substantial improvements. Additionally, high concentrations of added solvents have to be removed in additional process steps and possibly worked up and recycled.